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In order to make it removable, you're going to want to have a second drive shaft fabbed up that will fit in place of the rear drive shaft, which couples the motor in with it.

If you already have a carrier bearing in your drive shaft, you can add a support right to that area that will allow you a mounting location for the e-motor.

If you don't, you'll need to make a frame-mounted cross member that you can install the e-motor to.

Drive shaft shops can make your new e-motor combination shaft for ~$100 if you provide the donor drive shaft. If they charge more than that, they're ripping you off. It's about an hour of welding and 20 mins of cutting and measuring.